1. Field of the Invention
The present invention relates to a communication apparatus using space time coding for information communication, and more particularly to a communication apparatus configured to transmit or receive a space time code to test the receiving state of a receiver.
2. Description of Related Art
For a wireless communication system such as a mobile phone system, as a technique of raising the transmission rate without widening the frequency range, there is MIMO (Multiple Input Multiple Output) transmission that performs spatial multiplexing transmission using multiple transmitting and receiving antennas. For this MIMO transmission, in order to achieve a satisfactory diversity effect, signal points must be disposed per time and per transmitting antenna efficiently without lowering the coding rate excessively. Such signal point arranging method is called Space Time Coding (hereinafter, “STC” for short). As a typical space time coding, there is Space-Time Block Code (hereinafter, “STBC” for short). With a single receiving antenna, this technique can achieve a maximum transmit diversity effect equivalent to the maximum ratio composition.
With regard to STBC being a typical approach using STC, the following related art document (1) is known.
(1) A simple transmit diversity technique for wireless communication
S. Alamouti;
IEEE J. Select, Areas Commun., vol. 16, no. 8, pp. 1451-1458, October 1998.
According to the approach described in the document, a receiver can perform symbol separation by use of a simple linear calculation with respect to encoding by a transmitter, and also a maximum transmit diversity effect equivalent to the maximum ratio composition can be achieved. There are many applications of the approach, and there are many approaches for performance improvement when the number of antennas is greater than two; with regard to these approaches, there are the following related art documents, for example.
(2) Cyclic Space-Time Block Codes and Decoding Algorithm in MIMO CDMA System
Fu Hong-Hang; Feng Guang-zeng;
Wireless Communications, Networking and Mobile Computing, 2006. WiCOM 2006.
International Conference on 22-24 Sep. 2006 Page(s): 1-4
(3) A novel iterative receiver for coded MIMO OFDM systems
S. Sun, Y. Wu, Y. Li and T. T. Tjhung;
IEEE ICC 2004, pp. 2473-2477, vol. 4, June 2004.
Various combinations can be used in terms of the number of antennas of a transmitter or a receiver. According to the related art, however, no consideration has been given to mounting of LSI. For example, assume that there is demand that an STBC signal transmitted actually from an LSI is received and decoding of the STBC signal needs to be tested. However, when only an LSI of SISO (Single Input Single Output) based on wireless standard IEEE802.11n (hereinafter, “11n” for short) is arranged, the STBC signal test cannot be performed. Further, additional installation of a transmitter for the testing increases the cost. Thus, there is a need for an approach by which, in testing the transmitting and receiving state of the STBC signal, a change can be flexibly done to any configuration in terms of the increase and decrease of the number of antennas and the like, and the testing of the transmitting and receiving state can be implemented using an existing LSI chip.